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361.
Le Minh Nguyen Ting-Li Lin Yih-Min WuBor-Shouh Huang Chien-Hsin ChangWin-Gee Huang Tu Son LeQuoc Cuong Nguyen Van Toan Dinh 《Journal of Asian Earth Sciences》2012,43(1):241-253
The first attenuation relationships of peak ground acceleration (PGA) and peak ground velocity (PGV) for northern Vietnam are obtained in this study. Ground motion data are collected by a portable broadband seismic network in northern Vietnam as a part of cooperation between the Institute of Geophysics, Vietnamese Academy of Science and Technology, Vietnam and Institute of Earth Sciences, Academia Sinica, Taiwan. The database comprises a total of 330 amplitude records by 14 broadband stations from 53 shallow earthquakes, which were occurred in and around northern Vietnam in the period between 01/2006 and 12/2009. These earthquakes are of local magnitudes between 1.6 and 4.6, focal depths less than 30 km, and epicentral distances less than 500 km. The new attenuation relationships for PGA and PGV are:
log10(PGA)=-0.987+0.7521ML-log10(R)-0.00475R, 相似文献
362.
Pavel Pitra Marc Poujol Jean Van Den Driessche Jean-Charles Poilvet Jean-Louis Paquette 《Comptes Rendus Geoscience》2012,344(8):377-384
Dating the magmatic events in the Montagne Noire gneiss dome is a key point to arbitrate between the different interpretations of the Late Carboniferous–Early Permian tectonics in this southern part of the Variscan belt. The Saint-Eutrope orthogneiss crops out along the northern flank of the dome. We show that the protolith of this orthogneiss is an Ordovician granite dated at 455 ± 2 Ma (LA-ICP-MS U-Pb dating on zircon). This age is identical to that previously obtained on the augen orthogneiss of the southern flank, strongly suggesting that both orthogneiss occurrences have the same Ordovician protolith. The Saint-Eutrope orthogneiss experienced intense shearing along the Espinouse extensional detachment at ca. 295 Ma (LA-ICP-MS U-Pb-Th on monazite), an age close to that determined previously on mica by the 39Ar-40Ar method and contemporaneous with the emplacement age of the syntectonic Montalet granite farther to the west. This normal sense shearing reworked previous fabrics related to Variscan thrusting that can be still observed in the augen orthogneiss of the southern flank, and is responsible for the spectacular “C/S-like” pattern of the Saint-Eutrope orthogneiss. This work also shows that care is needed when dealing with C/S-type structures, since they can develop not only in syntectonic intrusions, but also in orthogneisses affected by an intense secondary deformation, at decreasing temperature. 相似文献
363.
Oleg G. Safonov Elizaveta I. Kovaleva Svetlana A. Kosova H.M. Rajesh Georgy A. Belyanin Maria A. Golunova Dirk D. Van Reenen 《地学前缘(英文版)》2012,3(6):829-841
Reaction textures and fluid inclusions in the~2.0 Ga pyroxene-bearing dehydration zones within the Sand River biotite-hornblende orthogneisses(Central Zone of the Limpopo Complex) suggest that the formation of these zones is a result of close interplay between dehydration process along ductile shear zones triggered by H2O-CO2-salt fluids at 750—800℃and 5.5—6.2 kbar.partial melting,and later exsolution of residual brine and H2O-CO2 fluids during melt crystallization at 650—700℃.These processes caused local variations of water and alkali activity in the fluids,resulting in various mineral assemblages within the dehydration zone.The petrological observations are substantiated by experiments on the interaction of the Sand River gneiss with the H2O-CO-2-(K,Na)Cl fluids at 750 and 800℃and 5.5 kbar.It follows that the interaction of biotite-amphibole gneiss with H2O-CO2-(K.Na)Cl fluids is accompanied by partial melting at 750—800℃.Orthopyroxene-bearing assemblages are characteristic for temperature 800℃and are stable in equilibrium with fluids with low salt concentrations,while salt-rich fluids produce clinopyroxene-bearing assemblages.These observations arc in good agreement with the petrological data on the dehydration zones within the Sand River orthoeneisses. 相似文献
364.
C. C. Bicalho C. Batiot-Guilhe J. L. Seidel S. Van Exter H. Jourde 《Environmental Earth Sciences》2012,65(8):2311-2319
The Lez karst spring, located in the Mediterranean basin (southern France) supplies drinking water to the metropolitan area
of Montpellier (France) since the nineteenth century. Since 1981, an intense pumping is being performed directly in the main
conduit with a maximum exploitation flow rate of about 1,700 l/s. To improve the understanding of groundwater origins and
circulation dynamic in this karst system, as well as the impact of three decades of intense water exploitation, groundwater
samples have been collected during various hydrologic conditions since March 2006. A previous hydrochemical study on the Lez
karst system had been carried out before the installation of the pumping plant. This dataset was compared to the present one
to identify possible changes on groundwater hydrochemistry. The results of this analysis indicate the existence of historical
changes in water hydrogeochemistry and evidence a decrease of the deep compartment participation to the Lez spring outflow.
This change in spring water hydrogeochemistry may be attributed to the intense pumping of the karst system and, in the absence
of noticeable climatic changes, expresses the direct consequences of anthropogenic forcing on the overall functioning of the
aquifer. This study aims to analyze the differences, to understand the water chemistry changes and to better foresee the aquifer
evolution for the future. 相似文献
365.
366.
Stien Heremans Bert Bossyns Herman Eerens Jos Van Orshoven 《International Journal of Applied Earth Observation and Geoinformation》2011
Artificial neural networks (ANNs) are a popular class of techniques for performing soft classifications of satellite images. They have successfully been applied for estimating crop areas through sub-pixel classification of medium to low resolution images. Before a network can be used for classification and estimation, however, it has to be trained. The collection of the reference area fractions needed to train an ANN is often both time-consuming and expensive. This study focuses on strategies for decreasing the efforts needed to collect the necessary reference data, without compromising the accuracy of the resulting area estimates. Two aspects were studied: the spatial sampling scheme (i) and the possibility for reusing trained networks in multiple consecutive seasons (ii). Belgium was chosen as the study area because of the vast amount of reference data available. Time series of monthly NDVI composites for both SPOT-VGT and MODIS were used as the network inputs. The results showed that accurate regional crop area estimation (R2 > 80%) is possible using only 1% of the entire area for network training, provided that the training samples used are representative for the land use variability present in the study area. Limiting the training samples to a specific subset of the population, either geographically or thematically, significantly decreased the accuracy of the estimates. The results also indicate that the use of ANNs trained with data from one season to estimate area fractions in another season is not to be recommended. The interannual variability observed in the endmembers’ spectral signatures underlines the importance of using up-to-date training samples. It can thus be concluded that the representativeness of the training samples, both regarding the spatial and the temporal aspects, is an important issue in crop area estimation using ANNs that should not easily be ignored. 相似文献
367.
Occurrence and distribution of microplastics in marine sediments along the Belgian coast 总被引:2,自引:0,他引:2
Claessens M De Meester S Van Landuyt L De Clerck K Janssen CR 《Marine pollution bulletin》2011,62(10):2199-2204
Plastic debris is known to undergo fragmentation at sea, which leads to the formation of microscopic particles of plastic; the so called ‘microplastics’. Due to their buoyant and persistent properties, these microplastics have the potential to become widely dispersed in the marine environment through hydrodynamic processes and ocean currents. In this study, the occurrence and distribution of microplastics was investigated in Belgian marine sediments from different locations (coastal harbours, beaches and sublittoral areas).Particles were found in large numbers in all samples, showing the wide distribution of microplastics in Belgian coastal waters. The highest concentrations were found in the harbours where total microplastic concentrations of up to 390 particles kg−1 dry sediment were observed, which is 15-50 times higher than reported maximum concentrations of other, similar study areas.The depth profile of sediment cores suggested that microplastic concentrations on the beaches reflect the global plastic production increase. 相似文献
368.
369.
Franois Jouanne Franck A. Audemard Christian Beck Aurlien Van Welden Reinaldo Ollarves Carlos Reinoza 《Journal of Geodynamics》2011,51(5):398-410
The right-lateral strike-slip El Pilar Fault is one of the major structures that accommodate the relative displacement between the Caribbean and South-America Plates. This fault, which trends East–West along the northeastern Venezuela margin, is a seismogenic source, and shows numerous evidence for active tectonics, including deformation of the Quaternary sediments filling the Cariaco Gulf. Because the main El Pilar Fault strand belongs to a set of strike-slip faults and thrusts between the stable Guyana shield (South) and the Caribbean oceanic floor (North), a GPS network was designed and installed to measure the relative motion of the El Pilar Fault and other faults. The results obtained from the comparison of 2003 and 2005 surveys indicate: (i) a lack of significant displacement (especially shortening) in the Serrania del Interior (Neogene cordillera overthrusted above the Guyana craton), (ii) an eastward displacement (relative to fixed south America plate) up to 22 mm/year of benchmarks located north of the El Pilar Fault. 相似文献
370.
Stijn Dhondt Quynh Le Xuan Hieu Vu Van Luc Hens 《Stochastic Environmental Research and Risk Assessment (SERRA)》2011,25(3):363-376
Traffic is an essential part of modern society and mobility is part of its socio-economic setting. However, signs of counter
productivity arise as the current mobility patterns substantially affect our health, including the consequences from traffic
accidents, air pollution—which causes even more victims than traffic accidents—and traffic-noise. The use of private motorised
vehicles also contributes to sedentarism, climate change and psychological effects. This paper reviews these mobility related
health effects and applies them to the situation in Hai Phong, a Vietnamese port-city in fast development and facing growing
mobility patterns. In his Master Plan the city developed a view on its development together with the transportation infrastructure
up to 2020. Together with the fast changing mobility patterns, such as a modal change from bicycles to motorcycles and cars,
this lead to an increase in motorized vehicles and non-negligible environmental health risks. Applying the methodology of
a Health Impact Assessment as used in previous studies the current health burden is estimated, focussing on particulate matter
(PM) and noise. For PM10 1287 deaths per year were calculated for the current situation, where the estimated number of deaths by 2020 doubled up to
2741. Hospital admissions due to PM10 raised from 44,954 now to 51,467 in 2020 and for PM2.5 the restricted-activity days were calculated, accounting for 852,352 per year. For noise only calculations for the current
state (2007) were performed. The total estimated DALYs due to noise was 4758. 相似文献